The purpose of the research is to gain insight into the control of renin in the adrenal medulla. The function of extra-renal renin is unknown. The highest concentration appears to be in the adrenal medulla. The methods to be used are similar to those used in the study of the cellular physiology and pharmacology of catecholamine secretion. They include studies on the subcellular distribution of renin and an analyzsis of factors which may affect its release from the adrenal gland will be those known to affect renin release from the kidney as well as those known to affect catecholamine release. Since renin is one of the humoral regulators of the cardiovascular system, an understanding of its control in an extra-renal tissue should aid in an understanding of physiological and pathological conditions.